Source: National Natural Science Foundation of China

Grant No:81661148053

Project: Odor representation across the two hemispheres

Chief Specialist: Prof.Fuqiang Xu

Abstract:

    The brain is composed from two inter-connected hemispheres, and information reaching one hemisphere is shared by the other hemisphere. How information is transformed across the two hemispheres is mostly unknown. For example, an odor perceived with one nostril occluded is easily recognized when the occluded and opened nostrils are switched. One possible mechanism is to assume that neurons with similar response properties in each of the hemispheres are inter-mutually connected. However, this assumption of precise bilateral functional connection has never been directly demonstrated.Furthermore, when the neural responses of sensory inputs are organized topographically, such in the visual or auditory systems, information can pass from one side to the other by
projection neurons that connect the appropriate topological maps. However, in olfaction it is generally accepted that odor representation in the olfactory cortex (OC) is not topologically organized on the anatomical level. Thus, it is unclear how commissural fibers can link neurons with similar odor tuning profiles. In this study, we aim to understand how odor information is represented across, and shared between, the two hemispheres. We hypothesize that neurons that have the same odor receptive fields in ipsilateral, and contralateral OCs are directly connected. To test this hypothesis, we will examine how OC neurons respond to a set of unilateral and bilateral odor stimulations. To gain insight into the mechanism by which OC neurons can be tuned to the same ipsilateral and contralateral odor stimulation, we will use advance and novel tracing techniques combined with optogenetic and computational techniques. The purpose of these techniques is to reveal the structural and functional connections between specific OC neurons and the two olfactory bulb projection neurons. We hypothesize that some neurons in the olfactory cortex integrate from the same glomerular patterns in both olfactory bulbs. Our study will shed light on how the two hemispheres communicate. This knowledge, in turn, can contribute to a deeper understanding of complex disorders such as epilepsy, schizophrenia, post-traumatic stress disorder, and autism, as these disorders are linked to impaired interhemispheric communication.